Bohag Bihu (mid-April, also called Rongali Bihu), the most popular Bihu celebrates the onset of the Assamese New Year (around April 14–15) and the coming of Spring. This marks the first day of the Hindu solar calendar and is also observed in Mithila,Bengal, Manipur, Nepal, Orissa, Punjab, Kerala and Tamil Nadu though called by different names. It's a time of merriment and feasting and continues, in general, for seven days. The farmers prepare the fields for cultivation of paddy and there is a feeling of joy around. The women make pitha, larus (traditional food made of rice and coconut) and Jolpan which gives the real essence of the season. The first day of the bihu is called goru bihu or cow bihu, where the cows are washed and worshipped, which falls on the last day of the previous year, usually on April 14. This is followed by manuh (human) bihu on April 15, the New Year Day. This is the day of getting cleaned up, wearing new cloths and celebrating and getting ready for the new year with fresh vigor. The third day is Gosai (Gods) bihu; statues of Gods, worshiped in all households are cleaned and worshiped asking for a smooth new year.
The folk songs associated with the Bohag Bihu are called Bihugeets or Bihu songs. The form of celebration and rites vary among different demographic groups.
Rongali Bihu is also a fertility festival, where the bihu dance with its sensuous movements using the hips, arms, etc., by the young women call out to celebrate their fertility. In this aspect, the bihu dance can also be called a mating ritual by the young men and women. Bohag Bihu or Rongali Bihu festival continues for seven days and called as Xaat Bihu. The seven days are known as Chot Bihu, Goru Bihu, Manuh Bihu, Kutum Bihu, Senehi Bihu, Mela Bihu and Chera Bihu.